A number of studies are directed to complexation of an organic material and an inorganic material. There have developed some organic/inorganic composite materials prepared by complexation of inorganic substances and an organic polymers.
As for organic polymers capable of containing a metal ion as a guest substance, it has been widely known that polyethylene oxide, compounds similar thereto, and graft polymers containing, as its side chain, polyethylene oxide or a compound similar to polyethylene oxide are organic polymers capable of containing, as a guest substance, a metal ion such as an alkali metal ion. Polyethylene oxide, compounds similar thereto, and graft polymers containing, as its side chain, polyethylene oxide or a compound similar to polyethylene are utilized as ion-conducting materials (Reference 1: Electronic Materials, ed. by the Society of Polymer Science Japan, Kyoritsu Shuppan Co., Ltd., pp. 279-290 (1992)).
High-molecular-weight organic metal complexes in which a transition metal such as copper, iron, cobalt, rhodium or the like is coordinate-bond with a polymer ligand are also known. (Reference 2: Naoki TOJIMA, Masao KANEKO and Mitsuo SEKINE, New Material for Polymers One Point-25, Polymer Complex, Kyoritsu Shuppan Co., Ltd., pp. 1-13, especially FIGS. 1.2 of page 4 (1990)) Such organic metal complexes with high molecular weight have the following properties: they are ease to be handled as raw materials, forming a complex to prepare them is easy, and they are highly effective. Examples of their functions are a synthesizing function (as catalysts, reagents), separating function, physiological function and physical function, and other functions.
Furthermore, various techniques to prepare an organic polymer containing fine metal particles by forming a complex with an organic polymer and fine particles of silver or gold are known. For example, (1) producing super lattice structure having a distinct structure by way of absorbing gold colloid and a cationic polymer alternatively, (2) physically synthesizing a polymer-metal nanoparticle complex by (i) preparing a metal nanoparticle through vacuum deposition, (ii) trapping the metal nanoparticle under a low temperature, and then (iii) stabilizing the metal nanoparticle by using the polymers, and (3) chemically synthesizing a polymer-metal nanoparticle complex by reducing a metal ion such as a gold ion, platinum ion, palladium ion, rhodium ion or iridium ion, using a reducing agent in the presence of a polymer stabilizer such as poly(N-vinyl-2-pyrrollidone)(PVP) or the like, (4) and other methods (Reference 3: Inorganic/Organic Nano Composite materials, Kagakusosetsu, Quarterly, No. 42, ed. The Chemical Society of Japan, Japan Scientific Societies Press, pp. 135-159 (1999)). It is also known to prepare a noble metal nanoparticle using a cationic isonitrile protectant having a relatively high molecular weight (having a hydrocarbon chain of 6 to 12 carbon numbers) (Reference 4: Tetsu YONEZAWA, Preparation of Noble Metal Nanoparticles Using a Cationic Isonitrile Protectant, Polymer Processing, vol. 51, No. 8, August, 2002 issue, pp. 343-347).
Some organic/inorganic composite materials containing a lamellar structure produced through intercalation are also known, though they are not many. For example, some organic/inorganic composite materials are also known wherein an inorganic lamellar substance such as graphite, a clay mineral, a metal oxide or the like is used and an organic substance is intercalated therein as guest molecules.
As another approach, the inventors of the present inventions and others reported recently that a lamellar crystalline organic polymer containing a carboxyl group can work as a host compound during intercalation and that the lamellar crystalline organic polymer can reversibly take (intercalate) an organic guest molecule such as an alkyl amine into a crystal thereof, the lamellar crystalline organic polymer obtained by crystalline polymerization of a muconic acid derivative or a sorbic acid derivative (Reference 5: Toru ODANI and Akikazu MATSUMOTO, Synthesis of Organic Lamellar Compounds by solvent-free process, Material Stage, vol. 1, No. 11, February 2002, Technical. Information Institute Co., Ltd. pp. 48-52).
All of the conventional organic/inorganic composite materials mentioned in References 1 to 4 are, however, prepared by using amorphous or partial crystalline organic polymers as their organic polymer or their organic compound with relatively high molecular weight. Amorphous or partial crystalline organic polymers are inferior to crystalline organic polymers in terms of thermostability, flame retardance, elastic constant, tensile strength, flexural strength, impact resistance, mar resistance, linear expansion coefficient, dimensional stability, shaping processability, electric properties, dielectric breakdown strength, dielectric constant, properties under high temperature, weatherability, resistance against hydrolysis, and the like property. Therefore the conventional organic/inorganic composite materials including the amorphous or partial crystalline organic polymer are inferior and need be improved in these properties.
In addition, because organic polymers and inorganic substances are poorly compatible with each other in general, it is difficult to attain homogeneous dispersion throughout in a material. Thus, in most cases, especially the physical method, the fine metal particles with the size from about several nanometers to several ten nanometers have been difficult to be dispersed in forming the conventional complex of fine metal particles and an organic polymer, and thus properties of the fine metal particle cannot be utilized effectively.
Furthermore, in all of the conventional organic/inorganic composite materials having a lamellar structure prepared by intercalation, inorganic substances are used as host compounds and organic substances are intercalated as guest molecules. An organic/inorganic composite material prepared by intercalating an inorganic substance intercalated as guest molecules in an organic polymer having a lamellar structure has not been known.
The intercalation into the lamellar crystalline organic polymer, which intercalation reported by the inventors of the present invention in the Reference 5, is to intercalate organic compounds as guest molecules. Intercalation of metal ion into a lamellar crystalline structure of an organic polymer is not known.